It was phased out in 2015 as that format is only 32bit. Here is an excerpt from the KB.

"However, note that export to U3D is no longer supported starting with SOLIDWORKS 2015. This old 32-bit only tesellation data format has been phased out in 2015 and replaced with the new 64-bit compiled application."

There is also an SPR to remove this from the help document for 2015 as it should no longer be in there.